This invention relates to methods and apparatus for folding sheet material to form a pleated packet of such size as to facilitate storage and transport thereof.
It is conventional to fold sheet materials in such manner as to form a packet of reduced area so as to facilitate the storage and transport of such packet. One instance in which the folding of sheet material is desirable is in the case of bags of the kind which are needed to assist in providing sterile zones adjacent an area in which surgical or other procedures are performed. Bags of this kind frequently are closed except for an open mouth at one end bounded by an elastic strip which partially closes the bag, but enables the bag to be supported by a suitable frame with the mouth open to shield the adjacent area. Such bags frequently are of large area ranging from 2 to 4 feet in width and 6 feet or more in length. The handling of such bags in unfolded condition is awkward and the preservation of the sterility of such bags is difficult to maintain. Accordingly, it is desirable to fold the bag by forming a plurality of pleats therein and produce a reduced area packet which more easily can be stored, transported, and maintained sterile.
Pliable sheet material is made into a bag having an open mouth at one end thereof which may be banded by elastic so as to cause the mouth to be urged toward a closed condition. The bag thus is formed of two layers of such sheet material and is closed along three of its sides, one of such sides constituting the bottom of the bag and the bottom being opposite the mouth. One closed side of the bag is introduced to a nip between a pair of rollers one of which constitutes a winding mandrel having openings in its surface in communication with a source of air pressure which selectively can be negative or positive. The mandrel is rotated so as to cause the bag to be wound convolutely into a roll, vacuum being applied to the bag via the openings in the mandrel to secure the sheet material on the mandrel and assure formation of a tightly convoluted roll. As the bag is rolled, an operator may maintain the elastically banded edge of the bag in stretched condition to avoid bunching of the sheet material.
Following completion of the roll the application of vacuum is discontinued and positive pressure is applied through the mandrel to the inner surface of the roll so as to enable the latter easily to be stripped from the mandrel. A clamp is applied to one end of the roll and the clamp moved in a direction to strip the roll from the mandrel. The roll is transferred to a position in which a portion of the roll overlies a pleating station at which a plurality of blades may be operated sequentially to crease the bag and form a pleated packet having a plurality of adjacent pleats.
Following pleating of the roll the clamp is released and the pleated packet is ejected from the pleating station for packaging or storage.